1. Field of the Invention
This invention relates to an abnormality diagnosing method of a valve apparatus such as electric valves (inclusive of solenoid valves) that can make diagnosis rationally and within a short time even during an operation of a plant and can convert maintenance of the valve apparatus from time management maintenance to condition monitor maintenance, and that can also make degradation estimation of the valve apparatus by use of database including the result of this diagnosis, a valve specification and a maintenance history including a periodical inspection plan and diagnosis, and eventually prepares a maintenance plan.
2. Description of the Related Art
Abnormality diagnosis of electric valves (inclusive of solenoid valves) and other valve apparatuses has been carried out in the past by opening a cover, changing the apparatus and fitting sensors.
However, to check the valve to be inspected by changing the valve and provisionally fitting the sensors, a power source must be cut off to insure safety, and the diagnosis can be conducted only during the stop of the plant operation. In addition, provisional jigs for removing the cover and fitting the sensors must be installed at a site having a limited space, and the majority of the working time is consumed by the fitting/removing work of the sensors when the restoration work after the diagnosis is completed is taken into account, too.
If all the sensors associated with the valve to be inspected are permanently installed for the purpose of diagnosis, the individual valves need the sensors and the sensor cables must be permanently laid down, thus inviting the problems of cost and management.
An apparatus for diagnosing a plurality of electric valves on the basis of consumed power of a motor by measuring an electric current and a voltage of power lines and control lines at a motor control center where driving power sources are concentrated to be controlled on a predetermined place is known as an apparatus that diagnoses the valve apparatus without changing it.
In this case, however, since the output (torque) of a driving portion is not measured, a minute change of the torque cannot be detected, in principle, particularly in a low load range. Therefore, the drawback remains unsolved in that the wear amounts of transmission elements of a transmission system and incomplete fitting of components cannot be detected. Further, it is theoretically impossible to judge the magnitude of mechanical inertia force after the feed of voltage and current to the motor is stopped and to judge whether or not the torque held by the electric valve after the stop of the motor is sufficient for cutting off a fluid.
Further, a conversion coefficient, that becomes necessary for converting electric power to the output torque of the driving portion, changes every moment, cannot be therefore known correctly and has low accuracy.
On the other hand, a diagnosing apparatus that has a torque measuring function indispensable for high precision diagnosis of a valve apparatus without opening and decomposing at all a cover and is applicable during the operation of a plant has not yet been developed at present.
It is an object of the present invention to provide a method and an apparatus for the method, for diagnosing abnormality and estimating degradation in a valve apparatus that can grasp abnormality and specify an abnormal position in the valve apparatus as a whole by using a driving force sensor provided permanently to the valve apparatus and provisional sensors adaptable by one-tough operation during a plant operation or a periodical inspection without changing at all the valve apparatus, can collectively conduct stipulation of a portion to be repaired, can limit an inspection range of the valve apparatus and can judge an abnormal sign to decide a repair timing of components and a maintenance timing by conducting the tendency management on the basis of the built-up data, and can be moreover practiced without a high level of skill.
According to the present invention, there is provided a method for diagnosing abnormality and estimating degradation in a valve apparatus, comprising the steps of connecting a driving force sensor provided to a driving portion of a valve apparatus to a diagnosing apparatus, provisionally fitting an energy sensor for detecting feed energy to the driving portion and a vibration sensor for detecting vibration of the valve apparatus to the valve apparatus; converting detection signals outputted from these three kinds of sensors to predetermined signals in a data conversion unit; conducting an analytical diagnosing processing of diagnostic data information for each diagnostic item by referring to an allowance value of each diagnostic item calculated from the specification of the valve apparatus and set in advance, and by referring to a maintenance record inclusive of the diagnostic result, to judge whether the valve apparatus is normal or abnormal; conducting further degradation estimation by conducting calculation with past diagnostic results, and preparing a future maintenance plan, thereby making it possible to conduct diagnosis from outside without opening and disassembling the valve apparatus and without cutting off the energy source even during the operation of the valve apparatus.
According to the present invention, there is also provided an apparatus for diagnosing abnormality and estimating degradation in a valve apparatus, comprising a data conversion unit including a driving force sensor for detecting driving force of a driving portion, built in the is driving portion of a valve apparatus and connected to a diagnosing apparatus, an energy sensor for detecting feed energy to the driving portion and a vibration sensor for detecting vibration of the valve apparatus that are provisionally fitted to the valve apparatus, the data conversion unit being used for converting detection signals outputted from these three kinds of sensors to predetermined signals; and
a processor connected to the data conversion unit, for collecting data, preserving accumulation of maintenance records including an allowance value of each diagnostic item calculated from the specification of the valve apparatus and set in advance and the diagnostic result, conducting an analytical diagnosing processing for each diagnostic item to judge whether the valve apparatus is normal or abnormal, conducting further degradation estimation while conducting calculation with past diagnostic results, and preparing a future maintenance plan, thereby making it possible to conduct diagnosis from outside without opening and disassembling the valve apparatus and without cutting off the energy source even during operation of the valve apparatus.
The present invention uses a small light-weight portable abnormality diagnosing/degradation estimating apparatus comprising a data exchange unit and a processor, a driving force sensor built in permanently, such as a torque sensor, and a provisional energy sensor for detecting a current such as a leakage current and a provisional vibration sensor for detecting vibration which provisional sensors can be fitted by one-touch operation, does not need to open a cover, etc, can conduct diagnosis within a short time without changing at all the valve apparatus not only during the stop of a plant operation but also during its operation, and can moreover manage a plurality of valve apparatuses.
Further, necessary data can be mutually exchanged among one processor having a database function and a plurality of processors each having a diagnosing function by respectively providing separate processors with the diagnosing function and with the database function (for managing data, valve specification, allowance value of each diagnostic item, diagnostic data, etc).
Moreover, it is possible to estimate degradation of each sliding portion and other movable portions and eventually to estimate their limit of use or exchange timing.